The integrity of the spine and its subcomponents like the vertebral bodies and intervertebral discs, both of which are well known structural body parts that make up the spine, is a key factor to maintaining a patient's good health. These parts may become weakened, damaged or broken as a result of trauma, injury, or disease (e.g., by tumor, autoimmune disease), or as a result of wear over time, or degeneration caused by the normal aging process.
In many instances, one or more damaged structural body parts can be repaired or replaced with a prosthesis or implant. For example, specific to the spine, one known method of repair is to remove the damaged vertebra (in whole or in part) and/or the damaged disc (in whole or in part) and replace it with an implant or prosthesis. In some cases, it is necessary to stabilize a weakened or damaged spinal region by reducing or inhibiting mobility in the area to avoid further progression of the damage and/or to reduce or alleviate pain caused by the damage or injury. In other cases, it is desirable to join together the damaged vertebrae and/or induce healing of the vertebrae. Accordingly, an implant or prosthesis for rigid fixation of the vertebrae may be utilized to facilitate fusion between two adjacent vertebrae. The implant or prosthesis may be implanted without attachment means, or fastened in position between adjacent structural body parts (e.g., adjacent vertebral bodies).
Typically, an implant or prosthesis is secured directly to a bone structure by mechanical or biological means. One manner of spine repair involves attaching a fusion implant or prosthesis to adjacent vertebral bodies using a fixation element, such as a bone screw. Most implants and their attachment means are configured to provide an immediate, rigid fixation of the implant to the implantation site. Unfortunately, after implantation the implants tend to subside, or settle, into the surrounding environment as the patient's weight is exerted upon the implant. In some cases, this subsidence may cause the rigidly fixed attachment means to either loosen, dislodge or potentially damage one or more of the vertebral bodies.
Several known surgical techniques can be used to implant a spinal prosthesis. The suitability of any particular technique may depend upon the amount of surgical access available at the implant site. For instance, a surgeon may elect a particular entry pathway depending on the size of the patient or the condition of the patient's spine, such as where a tumor, scar tissue, great vessels, or other obstacle is present. Other times, it may be desirable to minimize intrusion into the patient's musculature and associated ligamentous tissue. In some patients who have had prior surgeries, implants or fixation elements may have already been inserted into the patient's spine, and as such, an implant introduction pathway may have to account for these prior existing conditions.
Thus, it is desirable to provide an implant that can be easily inserted using minimally invasive retractor instrumentation in accordance with a specific pathway or approach. This facilitates a segmental or open approach to multiple levels of the spine. For example, in certain situations, it is desirable to provide a spinal implant that can be inserted at an oblique angle into the lumbar spine to avoid damage to the patient, while also being suitable for insertion by way of a minimally invasive approach.